I just finished a new build and have to share my experiences with the 5700 xt. Spoiler alert - I wound up going to Micro Center for a 2070 super instead.
I spent a couple days troubleshooting the following setup, all new from Amazon:
3700x
Tomahawk B450 max
2x8gb G-Skill 3600mhz cl16
Sabrent Rocket M.2 1Tb
Gigabyte 5700 xt gaming OC
Corsair cx750m
New windows installation, stock hardware settings. Memtest overnight, prime95 large 3 hours and small overnight, FurMark 3 hours - all passed, no temperature problems. Similarly, no problems when running gpu/cpu benchmarking tools. However, attempting to play any game, including Path of Exile, Borderlands 3, Outer Worlds, and more resulted in a sudden system reboot in less than 3 minutes, frequently at points of very low GPU load. Before the games crashed, the FPS and latency read fine, but the actual performance with stuttering and draw bubbles, was not that great.
I tried...
This morning I bought a 2070 super from Micro Center, was up and running with no problems in 5 minutes. Verified no problems in any games, very smooth play. Slight buzzing (mechanical?) sound but at least it works. I am sure there are people out there who have 5700 xts without these problems, but I want to add my voice to the list of reports of serious problems. I encourage people who are debating which card to choose to look up the comment history of people defending the 5700 xt - look at what they consider "minor" problems, how long they have to wait for working drivers for new games, look at how much time they spend posting on /r/AMD. And remember your time is money. I could have bought a 2080ti if I was working instead of fiddling with this GPU.